Motor Control: The Case For Intelligence
1 November 2011
Conventional low-voltage Motor Control Centres (MCCs) are ubiquitous in the oil and gas sector and, by and large, they are meeting the industry’s requirements for safe, reliable and efficient operation. So are there any real benefits to be gained by choosing the new generation of Intelligent Motor Control Systems (IMCSs) for future projects? The answer is undoubtedly yes except, perhaps, for the most undemanding of projects.
In a conventional MCC, the power switching and protection components that make up the individual starters are linked to the device that provides the control functions – most often a Programmable Controller (PLC) – with conventional cabling. In addition, the functionality of the components used, such as the protection devices, is defined within those devices. If additional information is required from the starters as an aid to managing the plant or for measuring and controlling energy usage, extra components have to be added, along with even more cabling to the PLC.
In an IMCS, things are rather different. The power switching devices are controlled by a Smart Control Unit (SCU) that also monitors the motor operating parameters, such as voltage and current. The protection functions are implemented in the SCU, which communicates with the PLC via a data connection. At a stroke, this approach eliminates much of the costly conventional control system cabling, replacing it with just a handful of network cables, at the most.
But the benefits go much wider. Because the protection functions of the starter are now defined by software in the SCU, decisions about these functions – and indeed about most of the other functions of the starter – don’t need to be finalised until after the motor control system has been built. This is a very attractive feature in oil and gas applications where late changes to plant configurations and specifications are common.
Furthermore, the functionality of the starters in the IMCS can be changed easily, quickly and inexpensively even after the plant has been put into service, providing the high degree of flexibility that today’s users demand. Finally, since the SCU directly monitors the operation of the motor and the starter, it can provide almost any operational data needed for plant management, energy reduction or maintenance purposes directly, without the need to install additional equipment.
It can be seen that IMCSs offer an extensive range of benefits, but there are still those who have reservations about their adoption. There are essentially two reasons for this. The first is that some of the earliest IMCS implementations were ill-conceived and failed to deliver on their promises. These issues have now been addressed – the technology has matured, and leading IMCS suppliers like Eaton are adept at leveraging that technology to maximise its benefits.
The second is that there are some applications where conventional MCCs are still the best option, though these are rapidly becoming fewer and further between. Typical of these are very simple installations where there is no requirement to collect data for onward transmission to a supervisory system and where the likelihood of modifications being needed during the life of the equipment is small. In such cases, a conventional MCC may well be both adequate and cost effective.
As a motor control equipment manufacturer that is a leader in the development and application of IMCS technology and that also offers an extensive family of well-proven conventional MCCs, Eaton is uniquely well placed to offer unbiased advice and guidance on choosing the best motor control solution for any application. Further, Eaton’s in-depth understanding of the oil and gas sector guarantees that this advice and guidance will be well attuned to the sector’s specific needs.
For further information, please visit www.eaton.com or contact Electrical: firstname.lastname@example.org Hydraulics: email@example.com